Aloe is a generic name of succulent plants belonging to Aloaceae of Liliales, and it is believed that there are 300 or more varieties. Among those, aloe vera has been said to keep the doctor away since a long time ago and has been used externally and internally as a folk remedy for a long time. Recently, functions possessed by aloe became attractive and are investigated for utilization in functional foods, supplements, medicaments, cosmetics, and the like. For example, dietary fibers are contained as major components in the aloe, and functional foods, supplements, medicaments, cosmetics, and the like which utilize this dietary fiber are investigated.
Although the dietary fibers contained in the aloe have not been known entirely, there are known water-soluble dietary fibers, namely, glucomannan and acemannan (Non-patent Document 1). In addition, Non-patent Document 2, for example, discloses that the dietary fibers contained in the aloe have physiological effects such as an immune stimulating effect.
It is also known that the aloe contains a trace amount of sterols. The trace amount of the sterol contained in the aloe was found to have an anti-diabetic effect (Non-patent Document 3). These phytosterols are known to exist focally as being surrounded by lipid bilayer membrane of a cell membrane.
Various technologies are being developed for manufacturing an extract in which the aforementioned functional components contained in the aloe are concentrated or for purifying the functional components. For example, Patent Document 1 discloses a method for obtaining a bitterness-free aloe extract by treating an aloe extract with a pectinase followed by adding an activated charcoal thereby allowing bitter components to be adsorbed. Patent Document 2 also discloses a method for manufacturing an aloe solution which has a reduced amount of a substance causing bitterness or astringency such as oxalic acid, is highly transparent, undergoes no precipitation, has a low viscosity, and is rich in mucopolysaccharides by treating an aloe mesophyll-derived solution with a pectinase followed by adding a calcium agent and filtration. Nevertheless, these methods are problematic because they allow the insoluble dietary fibers which are functional components of the aloe to be removed.
Patent Document 3 discloses a method for obtaining an aloe-derived polysaccharide concentrate by heating an aloe juice, adding a cellulase, conducting an incubation with stirring, inactivating the enzyme by heating, cooling, and then conducting filtration through charcoal, filter paper, and kieselguhr. As an alternative method for obtaining a similar composition, a method is disclosed in which an aloe gel is stirred and filtered through a filter paper, the resultant filtrate is decomposed enzymatically by adding a cellulase, the resultant solution is subjected to an ultrafiltration membrane to accomplish dialysis, and a retentate is obtained. Nevertheless, these methods are problematic because they allow the insoluble dietary fibers and phytosterols which are functional components of the aloe to be removed.
Patent Document 4 discloses a method for manufacturing an aloe vera extract containing phytosterols contained in a naturally-occurring aloe vera by a supercritical extraction. Patent Document 5 also discloses a method for recovering a phytosterol from a rapeseed oil and a soybean oil using methanol and a method for isolating a phytosterol by immersing a crude phytosterol in an organic solvent followed by separating the organic solvent off. Although these methods can concentrate the phytosterols contained in the aloe, they are problematic because they allow the dietary fibers which are functional components of the aloe to be removed. It is also problematic that a phytosterol, once isolated, becomes a waxy solid substance at ambient temperature or lower which is hardly miscible with water and difficult to be added to a food. Furthermore, an organic solvent is also problematic since it poses a substantial burden to the operator who uses it as described in Cited Document 5.
As another method, a method for manufacturing an aloe powder and an aloe juice having an aloin content of 50 ppm or less and a molecular weight of a contained polysaccharide of 400,000 dalton or more by immersing an aloe vera gel in water or an extremely dilute aqueous solution is disclosed in Patent Document 6. Nevertheless, this method is problematic since it allows, upon the aforementioned immersion, the water soluble dietary fibers to be eluted together, resulting in a loss of functional components of the aloe mesophyll.